The distribution of the incoming transmitted solar radiation (radiation which enters inside the greenhouse through canopy cover) on the floor and on the inner walls of the greenhouse has been studied to evaluated total solar fraction/solar fraction. Total solar fraction/solar fraction is required to write an energy balance equation for each component of a greenhouse. The evaluation has been done for different orientations of an even span greenhouse located at New Delhi (28.5 degrees latitude), India. The effect of length and the width of the greenhouse on the total solar fraction have also been evaluated. Three-dimensional shadow analysis in Auto-CAD has been used for the study. A typical clear day of winter and summer has been considered and it was observed that total solar fraction was higher in winter as compared to summer. Numerically, there is not much effect of orientation on total solar fraction of a day for a greenhouse. However, an orientation of 45 degrees clock-wise (for greenhouse initially at East-West orientation) resulted in lowest radiation loss during winter and maximum loss during summer. Total solar fraction plays an important role for smaller greenhouses. The methodology can be used for designing a greenhouse of any shape and size for any location. (C) 2011 Elsevier B.V. All rights reserved.